package com.summer.main;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * WavHeader辅助类,用于生成头部信息
 * @author chuanye.wan
 *
 */
public class WaveHeader {

       public final char fileID[] = {'R', 'I', 'F', 'F'};
       public int fileLength;
       public char wavTag[] = {'W', 'A', 'V', 'E'};;
       public char FmtHdrID[] = {'f', 'm', 't', ' '};
       public int FmtHdrLeth;
       public short FormatTag;
       public short Channels;
       public int SamplesPerSec;
       public int AvgBytesPerSec;
       public short BlockAlign;
       public short BitsPerSample;
       public char DataHdrID[] = {'d','a','t','a'};
       public int DataHdrLeth;

    public byte[] getHeader() throws IOException {
       ByteArrayOutputStream bos = new ByteArrayOutputStream();
       WriteChar(bos, fileID);
       WriteInt(bos, fileLength);
       WriteChar(bos, wavTag);
       WriteChar(bos, FmtHdrID);
       WriteInt(bos,FmtHdrLeth);
       WriteShort(bos,FormatTag);
       WriteShort(bos,Channels);
       WriteInt(bos,SamplesPerSec);
       WriteInt(bos,AvgBytesPerSec);
       WriteShort(bos,BlockAlign);
       WriteShort(bos,BitsPerSample);
       WriteChar(bos,DataHdrID);
       WriteInt(bos,DataHdrLeth);
       bos.flush();
       byte[] r = bos.toByteArray();
       bos.close();
       return r;
    }

    private void WriteShort(ByteArrayOutputStream bos, int s) throws IOException {
       byte[] mybyte = new byte[2];
       mybyte[1] =(byte)( (s << 16) >> 24 );
       mybyte[0] =(byte)( (s << 24) >> 24 );
       bos.write(mybyte);
    }


    private void WriteInt(ByteArrayOutputStream bos, int n) throws IOException {
       byte[] buf = new byte[4];
       buf[3] =(byte)( n >> 24 );
       buf[2] =(byte)( (n << 8) >> 24 );
       buf[1] =(byte)( (n << 16) >> 24 );
       buf[0] =(byte)( (n << 24) >> 24 );
       bos.write(buf);
    }

    private void WriteChar(ByteArrayOutputStream bos, char[] id) {
       for (int i=0; i<id.length; i++) {
          char c = id[i];
          bos.write(c);
       }
    }

}